Lighted signs are commonly used as a tool for identifying stores or other types of businesses. Often, these signs are formed from a series of discrete, three-dimensional letters. These letters, commonly known as "channel letters," typically include congruent front and/or back panels spaced apart by a rigid spacer band extending perpendicularly between the panel perimeters. The spacer band maintains the panels in a parallel, spaced-apart orientation. With this arrangement, the letters may be fitted with an internal light source and lit from within. Typically, at least the front panel of these letters is transparent or translucent, allowing light from within the letter to pass through the front panel, thereby illuminating the letter to passersby.
Various methods have been developed to efficiently and accurately produce these letters. The front and rear panels may be formed, for example, by cutting around a template or stencil. Letters may also be stamped from large sheets of material. Corresponding spacing strips, however, are harder to produce. Typically, the letter panel spacing strips are formed by cutting a strip of metal sheet stock to a precalculated length that is appropriate for a desired letter. Then, the strip is bent at a series of key locations to produce a bounded region that will follow the contours of the selected letter. The strips also often include edge flanges that increase structural integrity. Collectively, these flanges also form surfaces that allow secure attachment of the panels to the spacing strip. Additionally, the flanges may be used to secure the completed letter to a wall or other mounting surface.
Many devices have been designed to help form the spacing strips used in illuminated, or "channel" letters. For example, U.S. Pat. No. 5,367,902 discloses a metal sheet bending machine that uses a computer and an associated CCD camera to control the motions of a mechanized bending ram. The camera and computer of the '902 device cooperate with included light sources. These components work in concert during the bending of a metal strip to record and process a series of images taken while the metal strip is being bent. Real-time changes between the recorded images act as cues through which the computer guides the motion of the bending ram. The '902 device also displays the recorded images on a display, thereby allowing confirmation of the strip bending progress. Although the '902 device may help in some situations, the large number of components make this device cost-prohibative for many manufacturers. The '902 device also requires careful maintenance to ensure proper calibration of the various components.
Other devices also exist. For example, U.S. Pat. No. 5,377,516 discloses a method and apparatus for bending metal sheet stock. The '516 patent discloses a computerized system that produces a set of instructions for bending a suitable strip of metal into a letter-bounding shape. The included computer calculates the bends required to produce the desired shape and determines an appropriate sequence of bending that will produce the chosen shape without interference between the bending mechanism, the strip to be bent, and the already-bent portion of the strip. Once the bending sequence is identified, the device produces instructions and visual guides that may be printed directly onto the selected strip of material or that may be printed onto an adhesive label for subsequent application. Although the '516 device may provide some guidance to help direct bending, the '516 device does not ease the actual bending process itself.
Although the known methods may ultimately result in bent strips, they are very costly, both in terms of space required and in terms of purchase and maintenance costs. Thus, what is needed is a metal bending device that includes advantages of the known devices, while addressing the shortcomings they exhibit. The device should be inexpensive to obtain, simple to operate, and easy to maintain. The device should also be useable with strips having a variety of widths and thicknesses. The device should allow an operator to produce individual bends or a series of bends with equal ease. The device should also allow an operator to produce customized spacer strips for illuminated letters, with each strip having customized bends and a variety of angles.